98 Silver Bullet

iTrader: (28)

Can someone explain what this is, which hole are you actully drilling and what is up with epoxy?

Thanks

jimmyblue

iTrader: (11)

You fill the IAC and PCV ports with epoxy and
grind / blend to make the entire TB throat as
smooth to airflow as possible. Then, you have
to drill some holes (like 1/4", instead of
that 1"x1/2" lip / recess) to restore those
functions' air feed.

TheDogofWar

iTrader: (2)

it's easier to use a couple pens while filling in the gap to create the holes. Some leave them in and grind them off with the epoxy.

I coated mine with oil, packed in the epoxy and then pulled them out. Let it cure and started grinding.

Cal

iTrader: (1)

I've heard there is some machining that is done on TBs as part of the porting process. I want to port my own TB and have a lathe, but what needs to be machined? Also, if you open the throat up wouldn't you need a bigger butterfly valve so it will close all the way?

2001CamaroGuy

iTrader: (6)

DON'T midify the area where the butterfly is!!! That area just gets run over with a LITTLE wet/dry sandpaper to take out any scratches and such.

The area you are porting is BEFORE the butterfly.

The machining is on the TB stop to get you to 100%. That needs to be done on the car with AutoTap hooked up (you don't want to go past 100% or the computer will throw a code).

Cal

iTrader: (1)

Oh, OK I've already done the throttle stop mod, and I did use Autotap to get it right on. After I made that post I found a few how-to's on TB porting, learned that people avoid the butterfly area. But, what would be so hard about making a new over-sized butterfly? It's just a piece of aluminum sheet metal. From looking at the back of the TB casting in the pictures I saw, it would appear that there is plenty of meat there to allow taking out another 2mm or so.

TheDogofWar

iTrader: (2)

If I had a lathe I would go for it. If you can keep it symetrical there shouldn't be any probs.

eallanboggs

iTrader: (1)

If you mill away 2mm you should get a substantial increase in airflow. If you can run a lathe you should be able to fabricate a new butterfly in your sleep. You should also mill away the HUMP in front of the butterfly while your at it. That hump narrows down the ID of the TB.

Cal

iTrader: (1)

Yes, since I made those other posts I've learned you can gain a good amount just by cleaning up the stock air horn in front of the butterfly. At first I didn't understand how people were porting them because I could tell they were re-using the stock butterfly; I just assumed porting mean over-boring as well. True I could easily bore mine and cut a new butterfly, but I learned the problem with that is the TB will no longer fit on the intake manifold if I do that. Seems there is not enough meat in the intake to hardly bore it at all, and the gasket is a thin o-ring like thing very close to the edge. Looks like it would take a whole lot of JB weld or that Devcon no. 10110 Plastic Steel Putty to build it up. I decided that would be pretty expensive for the amount of gain I would get on my stock displacement engine, unless there is a cheaper material that would work.